(1) Field of the Invention
The present invention relates to a twin beam type headlight device for a motorcycle, having a pair of headlights, arranged left and right on the front face of a cowling that covers the front part of the motorcycle.
(2) Description of the Prior Art
To begin with, the luminous intensity distribution depending on the type of a bulb(light bulb) of a headlight for motorcycles will be explained. The case described here is assumed to be applied to a right-side traffic model and a left-side traffic model may be provided by reversing the right-side left.
FIG. 1 sectionally shows a typical example of a headlight. As shown in FIG. 1, it includes a reflector (reflecting mirror) b of a headlight a having a parabolic configuration. Recently, there has been a configuration in which a cut-less, clear or transparent lens c is used for the front face with a reflector b of a multi-reflector(multi-facet reflecting plate) so that a desired luminous intensity performance can be obtained by devising the shapes and arrangement of small mirror facets. Here, reference numeral d and e in FIG. 1 designate a headlight bulb(light bulb) and headlight housing, respectively.
In riding a motorcycle, if it runs on a two-way traffic road, not on a one-way traffic road, the headlight is set at the low-beam position so that the projection of the headlight will not dazzle the drivers on oncoming vehicles. In a motorcycle having a pair of left and right headlights, in the case of right-side traffic as shown in FIG. 2, for example, it is necessary to create a right-side higher luminous intensity distribution in which only the projection of the light on the left or on the oncoming vehicle""s side is set at the low beam position while the projection of the light on the right side or the opposite side is set at the high beam position. It should be noted that for a left-side traffic model, the distribution of light should be reversed right-side left.
Headlight bulbs for realizing the luminous intensity distribution as above can be roughly categorized into a double filament type shown in FIG. 3 and a single filament type shown in FIG. 4. A typical double filament type headlight bulb shown in FIG. 3 has two filaments f1 and f2 for low and high beams incorporated in a glass tube. A cup g is disposed beneath low-beam filament f1 and this cup g blocks the light emitted from the filament f1 so that light will not reach approximately the lower half of the reflector. Cup g is designed so as to meet the predetermined specification of luminous intensity distribution.
On the other hand, as shown in FIG. 4, a single filament type headlight bulb has no cup, hence light emitted from filament h is designed to reach the whole surface of the reflector. In order to attain the luminous intensity distribution as shown in FIG. 2, it is generally known that the reflectors for a single filament type and double filament type headlights should have hatched areas shown in FIGS. 5A and 5B as their reflective areas, respectively. As seen in FIGS. 5A and 5B, since in the double filament type headlight, light emitted from the low-beam filament is blocked by cup g, hatched portions A and B should be formed greater than those of a single filament type headlight. Particularly, the double filament type headlight is configured so that the distance from the center to a point H is greater than the distance from the center to a point K in the single filament type headlight.
Up to now, the luminous intensity distribution depending on the type of a headlight bulb has been described. To sum up, a double filament type headlight uses a reflector which can be switched between the high and low beam positions but needs greater reflective areas as shown by the hatching in order to satisfy the required luminous intensity distribution. A single filament type headlight uses a reflector which is dedicated for the high or lower position and can function with smaller reflective areas as shown by the hatching.
Referring next to FIGS. 6 and 7, the character lines of left and right headlights 10R and 10L will be described. FIG. 6 shows the character lines as the outline of headlights. FIGS. 7 and 8 are front and partial side views of a motorcycle. As shown in FIGS. 7 and 8, a leg shield j covering the front of an unillustrated steering head pipe is projected forwards over the front wheel. A pair of left and right cutout holes K (with their edges forming the character lines) are formed in the projected portion and a pair of left and right headlights a, a are embedded. A cover m is provided on the upper side of headlights a, a of leg shield j while a (lower edge) character line n of leg shield j is formed on the lower side of the headlights. A shield screen nxe2x80x2 and a pair of left and right rearview mirrors o, o are provided along the upper edge of leg shield j. A front turn signal o1 is provided on the front face of each rearview mirror o. A reference numeral p designates a front wheel; p1 a front fork; q a handlebar; and r a front leg shield-rear.
As to the motorcycle""s headlight, recently there has been a tendency toward twin beam type configurations in which a pair of separate lenses are arranged like xe2x80x98almond shaped eyesxe2x80x99 to create a stylish appearance or bold features. In FIG. 6, to create xe2x80x98almond shaped eyesxe2x80x99, the four vertexes A1(A2), B1(B2), C1(C2) and D1(D2) of each lens character are arranged so as to suffice the relation: distance A-B greater than distance C-D, and the figure becomes more like an almond shaped eye as the point D is positioned closer to the point C. Here, comparing FIGS. 5A and 5B with FIG. 6, to realize the right-side higher luminous intensity distribution(the luminous intensity distribution with the road-shoulder side higher in the right side traffic), the distance T-U of the reflector for a single filament bulb and the distance R-S of the reflector for a double filament bulb do not need to be very long.
FIG. 9 shows a configuration in which a pair of single filament type headlight reflectors are laid, on both the left and right side, over the xe2x80x98almond shaped eyesxe2x80x99 character lines (designated at k). FIG. 10 shows a configuration in which a pair of double filament type headlight reflectors are laid, on both the left and right side, over the xe2x80x98almond shaped eyesxe2x80x99 character lines. It is known from FIGS. 9 and 10, when comparing the position of each hatched portion with the character line k, the right-side headlight reflector in both the cases, has a large enough margin with respect to the character line while as to the left-side headlight reflectors for both the single filament and double filament, the hatched portion is positioned close to the character line. Particularly, in the case shown in FIG. 10, the part designated at H is located outside the almond shaped eye character line k0, which is needed so as to be stylish, hence it is impossible to achieve the required luminous intensity distribution if no countermeasure is taken.
To deal with this, the character line has to be spread outwards as indicated by k1 in FIG. 10. However, the lower right point D1 of the reflector also displaces outward, or downwards and rightwards, so that the boldness of almond shaped eyes is lessened.
However, as shown in FIGS. 9 and 10, in the prior art in which a pair of single filament type headlights are arranged on both the left and right sides, the headlight on the left side (oncoming vehicle""s side) should be allotted for that for low beam only while the headlight on the right side(road-shoulder side) should be allotted for that for high beam only, whereby only the left side low-beam only head light is activated in low-beam running, and the left side low-beam only head light and the right side high-beam only head light are both activated in high-beam running. Illustratively, when this motorcycle meets other vehicles running in the opposite direction, it should run in the normal travel mode or low-beam mode. Accordingly, only the left headlight for low-beam only is turned on. That is, there is a demand that both lights be lit up in order to improve visibility and improved appearance, but there has been no solution to meet this demand.
It is possible for the headlight configuration shown in FIG. 10 to turn both lights on during low-beam running, but the character line should be spread outwards in order to achieve the requirement of the luminous intensity distribution in the low-beam mode as mentioned above, which makes the almond shaped eye fat, lessening the bold appearance.
The present invention has been devised in order to solve the above problems, it is therefore an object of the present invention to provide a twin beam type headlight device for motorcycle, with which two lights can be turned on in the low-beam lighting mode so as to improve the visibility from the front and which can reduce the lights in diameter and hence reduce the area of the front projection of the cowling.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a twin beam type headlight device for a motorcycle, having a cowling that covers the front part of the body and a pair of headlights arranged side by side on the left and right sides on the front panel of the cowling, is characterized in that one of the paired headlights is a double filament type headlight which is switchable between low and high beams; the other is a single filament type headlight dedicated for low beam only; and a lighting controller which activates the low beam filaments of both headlights in the low beam mode and which activates the high beam filament of the double filament type headlight and the low beam filament of the other headlight in high beam mode is provided.
In accordance with the second aspect of the present invention, the twin beam type headlight device for a motorcycle having the above first feature is characterized in that the lens openings of the twin beam headlights are formed in an approximately elliptic shape that has major and minor axes or having an approximately parallelogram shape.
In accordance with the third aspect of the present invention, the twin beam type headlight device for a motorcycle having the above first feature is characterized in that the left and right headlights are laid out with their major axes inclined upwards and sidewards from the central axis of the vehicle, forming a roughly open-V shaped arrangement and each headlight has an optical element for achieving the predetermined luminous intensity distribution.
In accordance with the fourth aspect of the present invention, the twin beam type headlight device for a motorcycle having the above second feature is characterized in that the left and right headlights are laid out with their major axes inclined upwards and sidewards from the central axis of the vehicle, forming a roughly open-V shaped arrangement and each headlight has an optical element for achieving the predetermined luminous intensity distribution.
In accordance with the fifth aspect of the present invention, the twin beam type headlight device for a motorcycle having the above first feature is characterized in that on the assumption that the motorcycle travels on a two-way traffic road, a headlight including a double filament type bulb which is switchable between the low and high beams is arranged on the road-shoulder side, and a headlight for low beam including a single filament type headlight dedicated for low beam only is arranged on the center line side of the road.
In accordance with the sixth aspect of the present invention, the twin beam type headlight device for a motorcycle having the above second feature is characterized in that on the assumption that the motorcycle travels on a two-way traffic road, a headlight including a double filament type bulb which is switchable between the low and high beams is arranged on the road-shoulder side, and a headlight for low beam including a single filament type headlight dedicated for low beam only is arranged on the center line side of the road.
In accordance with the seventh aspect of the present invention, the twin beam type headlight device for a motorcycle having the above third feature is characterized in that on the assumption that the motorcycle travels on a two-way traffic road, a headlight including a double filament type bulb which is switchable between the low and high beams is arranged on the road-shoulder side, and a headlight for low beam including a single filament type headlight dedicated for low beam only is arranged on the center line side of the road.
In accordance with the eighth aspect of the present invention, the twin beam type headlight device for a motorcycle having the above fourth feature is characterized in that on the assumption that the motorcycle travels on a two-way traffic road, a headlight including a double filament type bulb which is switchable between the low and high beams is arranged on the road-shoulder side, and a headlight for low beam including a single filament type headlight dedicated for low beam only is arranged on the center line side of the road.